1. Field of the Invention
The present invention relates to vehicle antennas and more particularly, to a high-performance receiving antenna for receiving tire pressure signal used in a motor vehicle for receiving tire pressure signals.
2. Description of the Related Art
To avoid traffic accidents due to an excessive low tire pressure condition, the National Highway Traffic Safety Administration (NHTSA) has issued its final rule requiring all new passenger cars and light vehicles being manufactured for sale in the U.S. to be equipped with tire pressure monitoring systems (TPMS) by September 2007.
A known tire pressure monitoring system generally includes a sensor and transmitter unit installed in each of the vehicle tires, and a display device installed in the driver's cab. The sensor and transmitter unit detects the pressure of each of the vehicle tires and transmits each detected tire pressure signal to a wireless receiver at the display device in the driver's cab wirelessly, for display on the display screen of the display device in the form of a symbol or words. Subject to the symbol or words display on the display screen, the driver knows whether or not the tire pressure status of each of the wheels of the motor vehicle is under the normal range.
According to the aforesaid prior art design, the sensor and transmitter unit of the tire pressure monitoring system transmits the detected tire pressure signal to the wireless receiver at the display device in the driver's cab wirelessly during rotation of the wheels of the motor vehicle. The transmitting tire pressure signal will be attenuated  due to continuous rotation of the wheels of the motor vehicle. Further, because the tire pressure signal is being transmitted from the sensor and transmitter unit at the wheels of the motor vehicle to the wireless receiver at the display device in the driver's cab, the long distance transmitting of the tire pressure signal cannot avoid signal attenuation, and the wireless receiver at the display device may be unable to receive the tire pressure signal accurately.